renewable energy in zaanstad: from theory to practice - e-harbours

short term and have high short term fluctuations. As a consequence, their connection to the utility
network can lead to grid instability or even failure, if these systems are not properly designed or
controlled [5]. Among others, important aspects to consider with the implementation of distributed
generation into the distribution network are:
- Protection (tripping, fault levels, blinding of protection, etc.)
- Voltage limits
- Frequency
- Flicker
- Harmonic distortion
The impact of the implementation on the distribution grid has different effects for PV cells compared
to wind turbines. PV cells are connected on the low voltage network; wind turbines are usually
connected to the MV or sometimes even HV network. The injection of power from wind turbines and
PV cells affects both the voltage quality. Because the voltage level should be within limits at all times,
this is an important requirement and should be considered when plans are made for the
implementation of large quantities of solar and wind energy on the distribution network.
Although the current grids have evolved over more than a hundred year and have been performing
well, the implementation of large quantities of distribution generation on the distribution network
can cause problems in terms of reliability and power quality. A lot of research has been going on in
the field of automation of the current grid by communication and information technologies. A
common term used in this field of research is ‘Smart Grid’. Smart Grid however is a very broad term
and used in different contexts and different definitions. This is why it is important to define Smart
Grid and review the different concepts of Smart Grids. In the next section the definition, concepts
and capabilities of Smart Grid will be reviewed.
4.3 DEFINITION OF SMART GRIDS
The term Smart Grid has a lot of different definitions in the literature. Below are some examples
given.
‘A Smart Grid is an electricity network that can intelligently integrate the actions of all users
connected to it - generators, consumers and those that do both – in order to efficiently deliver
sustainable, economic and secure electricity supplies.’ (The European Technology Platform Smart
Grids)
‘A smart grid is the electricity delivery system (from point of generation to point of consumption)
integrated with communications and information technology for enhanced grid operations, customer
services, and environmental benefits. (US Department of Energy)
Although a lot of different definitions can be found in the literature, there are some basic similarities.
Integrating the key themes, a Smart Grid can be defined as the integration of ICT to the current
electric grid to enhance the sustainability, economic efficiency and security of electricity supply. A
Smart Grid is not really a new technology; it is rather a new combination of different existing
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